Sorry for a dumb question, but are you referring to the outside bulb won't blink when you signal or are you referring to the signal arrow in the car on the dashboard that won't flash?

Regardless, you can give them both a test. Just hit your hazzard button and check to make all the bulbs/arrows are flashing. If one bulbs isn't flashing then it's obvious that bulb is no good OR the wrong bulb is in there. If the bulbs are flashing but the internal arrow isn't, then the small bulb for that arrow is blown